Until now, Semantic Web applications have been a solution in search of a problem. There are some cool apps out there, but no killer apps ... at least not yet. I got excited when I saw the OpenCalais demo, but very few other people would get pumped about what basically boils down to a platform that tags, categorizes, and calculates relevancy for text content.

It kind of reminds me of the hype relating to grid computing. Everyone sees the potential, but when most apps address the needs of science and finance wonks, it's hard for the excitement to scale.